1. Field of the Invention
The present invention relates to a vehicle seat having an active headrest system and also relates to a lumbar support device.
2. Background Art
U.S. Pat. No. 7,044,544 discloses a vehicle seat back having a lumbar support element utilized as an activating element for an active headrest system. A lumbar support element of vertical operation is mounted on vertical rods having upper ends coupled to an impact body of the active headrest system. The lower ends of the rods are welded to a horizontal rod having opposite ends inserted into respective parallel guides that are secured to a lower cross beam of the frame of the seat back, with each of the guides defining an upwardly facing cam surface.
In event of a crash of the vehicle, the back of an occupant of the seat applies an impact force against the lumbar support element, which moves backward, and the aforesaid horizontal rod then slides on the cam surfaces. The lumbar support element and the vertical rods move back and are displaced upward as the rods transferring the relative movement to the impact body of the active headrest system. Thus, the lumbar support device contributes to the activation of the active headrest system, making the response to a crash situation more prompt.
The solution described in the cited prior document, while enabling a significant increase in the speed of intervention of the active headrest system, has some drawbacks. For example, the type of lumbar support used is not efficient from the standpoint of ergonomics and comfort, during normal use of the seat.